I am having the same issue... but with T-Mobile phone. We just replaced my husband's phone yesterday. I have disconnected his phone from the home wifi, physically taken out the sim card (which is laying on my desk), and if his phone is turned on, it will still get text messages. How? I have no clue. As long as the old phone is turned off, he can get messages on his new phone. Now, stranger still, the only person having issues sending messages to him is ME. He can get texts from anyone else with no problems, but my texts not so much. After an extended time, in order to get messages from me, he has to instigate the conversation and then my messages will come through. I spent over an hour at the t-mobile store this morning trying to get it fixed. The original issue was my corrupted contact file that transferred over when they set up his phone. so I deleted the contact and he could get messages from me... if the old phone was not in the area. Any suggestions on this one?